1. Field of the Invention
The present invention relates to an electronic device provided with an active mode, in which a directed process can be immediately executed, and a power saving mode, in which less power is consumed than the active mode, as operating modes and relates to a method for controlling the electronic device, etc.
2. Description of the Related Art
Recently, a mechanism that suppresses power consumption has been introduced in electronic devices. For example, electronic devices (for example, image forming apparatuses, etc.) provided with an active mode in which processing units are kept active so that processes directed by a user can be immediately executed and a sleep mode (power saving mode) in which consumed power is reduced by activating the processing units after directions are given have been invented. Such an image forming apparatus switches from the active mode to the sleep mode when predetermined time (mode set time), which is set in advance, elapses after a process such as a copying process or a printing process is finished. In the sleep mode, power supply to an image forming unit, which is not relevant to transmission and reception of directions of process execution, is stopped. When a direction of process execution is received in the sleep mode, the power supply is resumed. Then, after the image forming unit is recovered and becomes operable, an image forming process can be executed. Particularly, warm-up of the image forming unit is required in the image forming apparatus; therefore, it takes time until it is recovered from the sleep mode and the process becomes executable.
Therefore, the techniques aimed at reduction of waiting time and power saving in the image forming apparatuses have been studied. For example, Unexamined Japanese Patent Application KOKAI Publication No. 2005-153226 discloses an image forming apparatus which continuously supplies power to a reader/writer within weekly timer set time (power-distributed period) since image forming operations are frequently carried out in many cases and prioritizes an energy saving measure except the weekly timer set time (dormant period) since image forming operations are not frequently carried out. In such image forming apparatus, within the weekly timer set time, advancing power saving is difficult since power is continuously supplied. Therefore, in order to advance power saving, it is conceivable to set the mode set time of the image forming apparatus to the shortest time upon shipment. However, when the mode set time is short in this manner, the image forming apparatus is immediately changed to the sleep mode. In this case, a user who frequently uses the image forming apparatus intermittently waits over and over until the apparatus recovers from the sleep mode.
Therefore, the user sometimes changes the setting of the mode set time so that it becomes longer. However, when the mode set time is extended in this manner, not so much contribution for power saving is made by the sleep mode.